British Astronomical Association
Supporting amateur astronomers since 1890

Secondary menu

Main menu

Home Forums Comets
Terms of use

spectroscopic cross section through C/2020 R4 ATLAS

8 posts / 0 new
Last post
Robin Leadbeater's picture
Online
Last seen: 7 min 50 sec ago
Joined: 05/03/2014 - 00:50
spectroscopic cross section through C/2020 R4 ATLAS

A cross section through the coma  using the same technique as for 2020 F3 NEOWISE

https://britastro.org/jbaa/pdf_cut/jbaa_24438.pdf

fig 4a

The most obvious differences are that sodium emission is absent and the C2 distribution in 2020 R4 is similar to that of CN, broader than in 2020 F3  

Cheers

Robin

Derek Robson's picture
Offline
Last seen: 2 months 3 weeks ago
Joined: 04/12/2017 - 02:41
NEOWISE Article

Robin.  A pretty neat article.  Around the time when the comet was visible night and morning, I took a mixture of images on a Star Adventurer with a 300 mm lens.  On some of the wide angle images with the standard 18-55 mm lens, I used a diffraction grating.  I didn't do anything with the images at the time, but meant to go back one day.  The magnification with a wide angle is quite small though. Although the tail came out very bright and sky had a glow to it, I'm not sure if there was any faint diffraction pattern. I should go back and check in negative format.  That was the night my car battery failed when I was out in the countryside and I didn't know my location :(

Robin Leadbeater's picture
Online
Last seen: 7 min 50 sec ago
Joined: 05/03/2014 - 00:50
sodium tail ?

Hi Derek,

What date was this ?  Objective grating setups showed a nice little sodium coma and tail.

My early example on 7th July

https://britastro.org/comment/8806#comment-8806

and a better one a few days later by Mike Harlow

https://britastro.org/comment/8832#comment-8832

but the sodium dropped in intensity after that and was lost in low resolution spectra around 22nd July

Cheers

Robin

Derek Robson's picture
Offline
Last seen: 2 months 3 weeks ago
Joined: 04/12/2017 - 02:41
NEOWISE

Hi Robin
This image was taken on 12th July where I went out. But I will have some others around that date. I will check. But I think I only tried the diffraction grating on 12th until it misted up then reverted to without grating.
I can't be sure of the orientation of the lines now, and at the time, I was puzzled by the lack of obvious spectra from some of the brightest stars (unless they were out of field).  

Robin Leadbeater's picture
Online
Last seen: 7 min 50 sec ago
Joined: 05/03/2014 - 00:50
Reduced spectrum of coma

The spectrum of the central coma is now on my BAA observer's page here

Derek Robson's picture
Offline
Last seen: 2 months 3 weeks ago
Joined: 04/12/2017 - 02:41
NEOWISE 2

Derek Robson's picture
Offline
Last seen: 2 months 3 weeks ago
Joined: 04/12/2017 - 02:41
NEOWISE 1

1

Derek Robson's picture
Offline
Last seen: 2 months 3 weeks ago
Joined: 04/12/2017 - 02:41
NEOWISE 4

Hi Robin

Just looked again at the widest angle image. At the bottom, there are a few lamps which show the dispersion is roughly horizontal (on that image anyway).

Derek